Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 4: Graphene I
O 4.4: Vortrag
Montag, 26. März 2012, 11:15–11:30, MA 041
Wave function mapping of graphene quantum dots with soft confinement — •Dinesh Subramaniam1, Florian Libisch2, Yan Li3, Christian Pauly1, Viktor Geringer1, Raphel Reiter2, Torge Mashoff1, Marcus Liebmann1, Joachim Burgdörfer2, Carsten Busse4, Thomas Michely4, Riccardo Mazzarello3, and Markus Morgenstern1 — 1II. Physikalisches Insitut B and JARA-FIT, RWTH Aachen University, D-52074 Aachen, Germany — 2Institute for Theoretical Physics, Vienna University of Technology, A-1040 Vienna, Austria — 3Institute for Theoretical Solid State Physics and JARA-FIT, RWTH Aachen University, D-52074 Aachen, Germany — 4II. Physikalisches Institut, Universität zu Köln, Zülpicherstr. 77, D-50937 Köln, Germany
Using low-temperature scanning tunneling spectroscopy, we map the local density of states of graphene quantum dots (QDs) supported on Ir(111). Due to a band gap in the projected Ir band structure around the graphene K point, the electronic properties of the QDs are dominantly graphene-like. Indeed, we compare the results favorably with tight binding calculations on the honeycomb lattice based on parameters derived from density functional theory. We find that the interaction with the substrate towards the edge of the island softly opens a gap in the Dirac cone, which implies soft-wall confinement. Interestingly, this confinement is required for highly symmetric wave functions. Further influences of the substrate are given by the known moire potential and a 10 % penetration of an Ir surface resonance into the graphene layer.